Nuclear reactor and production systems with digital controls

ABSTRACT

Several digital sensing devices are described for use in automated production systems. The first described is for use in the automatic operation of a reactor. This device employs a binant electrometer using a quartz fiber mounted at one end but free to vibrate at the other in an AC field. The fiber oscillates if a charge is placed upon it. An optical slit replaces the ordinary eyepiece reticule scale. With the quartz fiber adjusted so its image is in focus at the optical slit, photoelectric signals are obtained at null charge on the fiber. The quartz fiber is repeatedly charged and allowed to discharge by collecting ions from a source under measurement. Each photoelectric signal causes a digital time reading to be taken. The time readings are used to evaluate the current due to the collected charge. The photoelectric signals, by feedback, also operate the electrometer for continuous or intermittent-continuous operation. Basically, the system is a current digitizer. Application is made to reactor monitoring and control as well as to other types of production systems. Finally, other types of sensing devices are also described and their use in automated controlled processes is shown.

This invention is a continuation-in-part of the previous applicationSer. No. 238,036, filing date of Mar. 27, 1972 and entitled "NUCLEARREACTOR AND PRODUCTION SYSTEMS WITH DIGITAL CONTROL" now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to deflection instruments and their use for themeasurement of various kinds of forces; in particular, it relates to animproved method and means for the continuous monitoring and recording ofthe phenomena measured by such instruments. In certain respects, thisapplication is similar to a former publication, U.S. Pat. No. 2,986,697.However, it contains substantial improvements and innovations beyondthose described in the earlier patent.

In many deflection instruments, the forces deflecting the movableelement are subject to a field of force of one kind or another: wherethe relationship between the field and the forces or between the forcesthemselves are known, measurements may be undertaken. For example, whenan electrostatic field of force controls the movement of a member thatis collecting an electric charge, an electric current may be measured.Known physical laws relate the average current and the rate ofdeflection of the movable element.

More in particular, it is often desirable to use a quartz fiberelectrometer in conjunction with an ionization chamber for radiationmeasurements. A well-designed electrometer is sufficiently accurate tobe employed as a secondary standard but requires operator observation ofthe rate of deflection of the electrometer needle. The need forcontinuous operator attention has inhibited use of an electrometer forroutine measurements despite its many desirable characteristics.

It is therefore an object of this invention to provide an improvedmethod for the automatic monitoring of the phenomena measured by suchdeflection instruments.

It is also the object of this invention to provide other types ofdeflection instruments which are useful in various manufacturing,production or controlled process operations. These new types ofdeflection instruments have similar properties to the automaticallyoperated electrometer which will first be described.

The electrometer is a deflection instrument having a movable element inan electric field of force. Since the field is electric the forces willbe produced by electric charges (of opposite sign) supplied to themoving element. Also, associated with this instrument is a source ofillumination and an optical system adjusted to focus the real image ofthe deflection element (usually provided in the form of a needle clampedat one end and free to vibrate at the other) upon an optical mask havingone slit thereon. A photoelectric cell is either mounted behind the slitor is connected to the slit by means of fiber optics so that signals maybe generated when the deflection element is in a null condition. Thesignals generated through the instrumentality of thereal-image-optical-slit-photocell arrangement are then employed both tooperate a feedback control for the instrument itself, as well as tocontrol digital time counters and recorders, thus to store in memorydigital information of the rate of change of the potential of the needledue to the charge accumulating thereon.

In employing such a unit of invention in connection with an ion chamberand a quartz fiber needle electrometer for the measurement of radiation,the "rate of charge" or "drift" method is employed and currents of lessthan about 10-¹⁶ ampere may be measured.

In the device first to be described, time is the dependent variable andis the principal quantity under measurement. Independent variables, suchas voltage, may be set by control nobs or are variables to be measured,as is the electric current with quartz fiber electrometers. Constantsare either built into the device or are set by controls. As a result,all measurements appear as digital, time-interval readings. This makesit natural for automatic readout as on a tape or card together withvisual display of the reading if desired.

The arrangement thus generally described provides for fully automaticoperation of the scaler or digitizer eliminating the necessity forattendance by a trained operator. As a digitizer the instrument makespossible the change of information from analog to digital form. Anotherimportant object of this invention is to describe an automatic method oftaking current measurements with an electrometer on a continuous basis.

This is possible since the time required for sensitivity measurements iscompletely eliminated and the dead time between measurements may be aminimum, constant time interval, (less than a second). Thus, allmeasurements can be made in real time.

A further object of this invention is to apply this digitizing,flux-measuring equipment to the control of a nuclear reactor. Not onlydoes such a digitizer afford a means of obtaining reactor flux levels atseveral places simultaneously in the core lattice, and at frequent,almost continuous intervals, but these readings may be further used toobtain automatic control of the reactor's power output.

Another object of this invention is to employ rotating arm or deflectingarm instruments as optical, analog-to-digital converters. In theseinstruments, the real image of the deflecting arm may be used to derivetime interval measurements in an optical slit-phototransducer system; orthe moving arm itself may cause the interruption of optical fluxincident upon the optical-slit-phototransducer arrangement.

The following description and accompanying drawings will more fullydescribe the purpose of this invention:

IN THE DRAWINGS

FIG. 1 shows a block diagram of a precision radiation measuring device.

FIG. 2 is a block diagram illustrating the basic components of a systemsuitable both for nuclear reactor flux level measurement and poweroutput control.

FIG. 3 indicates the general arrangement of one form of apparatusembodying the invention.

FIG. 4 illustrates the optics associated with the electrometer in anembodiment of the invention.

FIG. 5 illustrates an optical slit with the needle in a nulled, i.e.,equilibrium position.

FIG. 5A illustrates a mechanical, adjustable optical slit, opened foradjustment purposes.

FIG. 5B illustrates the same optical slit shown in FIG. 5A but rotatedso as to further facilitate adjustment.

FIG. 6 shows a fixed optical slit together with an auxiliary slit usefulfor making optical alignment adjustments.

FIG. 7 illustrates an arrangement of electrical circuits useful in thepractice of the invention.

FIG. 8 shows a schematic circuit diagram for the AC potential supply forthe vibrating fiber electrometer.

FIG. 9 shows one method for making automatic adjustment ofpotentiometers for AC null control.

FIG. 10 is an optical-aperture, rotating arm light chopper -- simplycalled a light chopper. It is useful in changing analog to digitalsignals.

FIG. 11 is an optical-aperture, rotating arm angle indicator useful as arate meter.

FIG. 12 is a flux driven, optical-aperture, rotating arm, light chopperuseful in changing signals from analog to digital. It is designed toemploy radiant flux as its driving force. A side and top view are shown.

FIG. 13 shows the components of an optical digitizer.

FIG. 14 shows the components of a flux-optical digitizer.

FIG. 15 shows the components of a spectro-optical digitizer and thespectral source.

FIG. 16 shows the components of a spectro line-intensified digitizer.

FIG. 17 shows a general arrangement to obtain automatic control ofreagent input to a reactant vessel and for temperature regulation of thevessel.

Referring now to the block diagram of FIG. 1, a general purposeprecision radiation measuring system is shown. It is comprised of thefollowing:

1. an ion chamber, indicated at 1a,

2. An electrometer indicated at 1b,

3. A phototransducer and optical slit system, indicated at 1c,

4. a DC potential for the ion chamber, indicated at 1d,

5. an AC potential for the electrometer, indicated at 1e,

6. a source of illumination for the optical system, indicated at 1f,

7. a DC bias potential and bias control for the electrometer, indicatedat 1g,

8. a control unit containing logic to control the electrometer, as wellas the systems time interval measuring units, indicated at 1h,

9. high and low frequency pulse sources, indicated at 1i,

10. an OR gate to pass one of the selectable frequencies, indicated at1j,

11. an AND gate for passing pulses to the counter during the timeinterval which is to be measured, indicated at 1k,

12. the primary counter and associated logic, indicated at 1L,

13. output instrument or instruments for recording the time intervals,indicated at 1m,

14. a visual display of each time interval reading may also be employed,indicated at 1n.

IN FIG. 2 the digital electrometer scaler, adapted for use as a controlsystem, is seen to comprise the following:

1. an ion chamber, indicated at 2a,

2. an electrometer, indicated at 2b,

3. a source of fixed potentials for control of the electrometer and ionchamber, indicated at 2c,

4. an electrometer control circuit, indicated at 2d,

5. the adjustable bias potentials for electrometer control, indicated at2e,

6. an optical-slit system and a phototransducer assembly, indicated at2f,

7. a high resolution counter-timer, and logic, indicated at 2g, Thelogic performs those functions previously described for FIG. 1 at 1h,1i, 1j, 1k, and 1L,

8. a time interval memory, indicated at 2h,

9. a computer unit, indicated at 2i,

10. control logic responsive to the photoelectric signals for control ofelectrometer potentials as well as the control of a nuclear reactor orother device, indicated at 2j,

11. a control system, which may be a set of control rods, a waterdumping system or a scram control--in the case of a nuclear reactor; ormore generally, a control device for other systems, indicated at 2k,

12. a nuclear reactor or other device under control, indicated at 2L.

Each of these components will be considered in more detail after adescription of the electrometer itself.

The Shonka electrometer has recently appeared on the commercial marketbearing the name of its designer. It is a highly sensitive quartz fiberinstrument of rugged design and as such is desirable for reactor controlapplications. In conjunction with the novelties of this invention, itmay also serve as a general purpose, high precision radiation measuringinstrument. The heart of this binant electrometer employs a conductingquartz fiber which is clamped at one end but free to vibrate on theother. The free end is mounted so it may vibrate in an alternatingelectric field maintained between two fixed electrodes or binants. Thequartz fiber needle will vibrate in the AC field if either of twoconditions is met:

1. the fiber bears an impressed DC potential, or if

2. there is more AC potential on one binant than the other. But ifneither of these conditions obtain, the quartz fiber or needle will beat rest, in both AC and DC equilibrium in the AC field. It may be notedthat a DC bias potential is sometimes applied, not directly to the fiberas in 1) above, but is superimposed upon the AC potential applied to thebinants. This has the effect of producing more potential on one of thebinants than the other. Either of these two biasing methods may be usedin the automatic operation of the electrometer.

Under automatic operation, the eyepiece reticule, against which oneordinarily observes the quartz fiber either at rest or fanned out invibration, is replaced with a single optical slit, and if suitablecontrol is employed, the Shonka electrometer may be operated on a fullyautomatic basis. The single slit may be so adjusted that the real imageof the electrometer needle is focused on the slit when the needle is atrest in the AC field.

Although the Shonka electrometer is supplied for commercial use with areflecting mirror-optical system, it has been found that a refractinglens system gives more positive operation with thisphotoelectric-optical-slit method of readout which is to be described.It may be noted that either mirror or lens system may be employed withthis invention.

With a single slit-optical system, used in conjunction with the Shonkaalternating current field electrometer, control circuitry becomessimplified since every reading with the instrument, after the initialreading, is a radiation measurement. This contrasts favorably withrespect to the older, double-slit, aforementioned patent publication,which double slit system requires circuitry for distinguishing fourtypes of measurements.

The structure shown in FIGS. 3 and 4 show two of various arrangements ofion chamber, electrometer, photomultiplier and optical system. Electriccharge from the ion chamber 43 (FIG. 3 only) to the electrometer quartzfiber needle, the end view of which is shown at 34, causes the needle,which initially oscillates between positions 35 and 31 (FIG. 4 only), tocome to an equilibrium or rest position. The charge-biased needleoscillates because of the AC field which is produced by applying analternating current through wires 36 and 37 to the electrometer binantelectrodes at 20 and 21. In FIG. 3 is shown a supporting base 30 whichcarries a source of illumination at 31. (This source of illumination isnot shown in FIG. 4). The electrometer housing 33 permits light incidenton the quartz fiber needle 34 to reach the lens 53. The lens is soadjusted that the real image of the fiber needle is focused on theoptical slit 40, contained in the mask 39. The mask containing theoptical slit is in the focal plane of the lens 53; a photomultipliertube contained in the housing 60 is thereupon illuminated by lightproceeding through slit 40.

In FIG. 4 the optical path is increased by employing prisms 54 and 55.The housing 58 holds the electrometer housing 33. Support 61 holds theoptical slit mask 39 in related operating adjustment to thephotomultiplier housing 60. Support 61 also holds prism 54. Support 62can be seen to hold prism 55 in addition to a housing for lens 53. Theoptical path 10 is indicated by the dotted line.

In FIG. 3, housing 137 holds the optical slit mask 39 in the plane offocus of the real image of the needle 34. Although the diagrams showlens 53 employed to form this real image, it might have beenaccomplished by means of a reflecting mirror arrangement as used in thecommercially available Shonka electrometer.

In FIGS. 5, 5A and 5B is shown a mask 39 and an optical slit 40,together with a superimposed real image 34 of the electrometer needle.The optical slit may be fixed or adjustable. The slit, if fixed, isruled on an opaque mask. The mask may be a glass reticule made opaque bycoating. The coating may be a metal, such as copper and silver,sputtered onto the glass. The ruling is usually machine controlled, thusremoving the coating to any desired specification of width.

FIG. 5 shows an optical slit in adjustment with the real image of theelectrometer needle blocking out most of the illumination. The decreaseof illumination due to the presence of the real image of the needle issufficient to produce a photoelectric control signal.

FIG. 5A shows an adjustable, mechanical slit, desirable for the practiceof this invention, in that it may be opened, as shown, to facilitateone's viewing and adjustment of the real image of the electrometerneedle.

FIG. 5B shows the adjustable slit of FIG. 6 in a rotated position tofurther facilitate viewing the real image of the electrometer needle andfor making adjustments of the optical system.

One may employ a ramsden eyepiece (not shown in the drawings) forviewing the optical slit and needle image; it is necessary, of course,to first remove the photomultiplier and the photocell housing, or thefiber optics, as the case may be, from its position above the opticalslit. Then a ramsden or equivalent eyepiece is set in place above theslit and adjustments may be made.

FIG. 6 shows two fixed slits 40 and 60, arranged on mask 39. Theauxiliary slit 60 is perpendicular to, but also may be at an angle withrelation to the principal slit 40. The auxiliary slit is usuallynarrower than the principal one, since its purpose is to aid the eye tolocate the image of the needle and in positioning mask 39 while makinginitial adjustments. The initial adjustment of mask 39 requires thatwhen the image of the needle is at mechanical rest, that is, at AC andDC null, it should be in some degree of overlapping relationship withslit 40.

FIG. 7 shows three sources of potential and three circuits useful inoperating the system. At 500, the ion chamber potential is shown. Theion chamber is comprised of the chamber itself at 43 holding acollecting electrode 544 by means of a double circular insulator 541 and543. To a conducting ring 542, supported between the high dialecicinsulators 541 and 543, is attached the grounded end of the ion chamberpotential 500. The high side of this potential is placed on the outerwall of the chamber.

Ions are produced in the chamber by incident radiation, 577, fromsource, 576, partially surrounded by shield 575. Low radiation levelsource material may be conveniently placed within the ion chamber.

A small relay with closing coil shown at 534, and moving armature at512, fits inside the electrometer case, 33, adjacent to the binantelectrometer shown at 550. This relay armature carries a smallcontactor, 513, adjusted to make and break contact with the collectingelectrode, 544, of the ion chamber. Contactor 513 carries a potentialfrom source 510 which is adjustable through potentiometer 511. Thisbiasing potential is capable of setting the electrometer needle, 34, inoscillation when the needle is in an AC field.

Another potential at 530 controls relay coil 534 and is capable ofremoving contactor 513 and thus removing the source of bias 510 from theelectrometer-ion chamber-conducting electrode comprised by 34 and 544 inconnection.

It may be noted that the bias supplied by potential source 510 must beopposite to the charge collected by the ion chamber due to the impressedpotential from source 500.

The mode of operation of the electrometer in conjunction with thesingle-slit-photoelectric arrangement will now be described.

Referring to FIG. 7, the electrometer quartz needle 34 and ion chambercollecting electrode 544 are permanently connected. Together theyconstitute the systems charge-holding conductor. This conductor mayreceive charge in two ways. Either from the ion chamber or throughcontactor 513 from potential source 510 which is adjusted by potentialdivider 511.

After contactor 513 is withdrawn from the charge-holding conductor34-544, charge produced in the ion chamber 540 due to radiation 577 fromsource 576 in shield 575 is collected onto the charge-holding conductorsystem. On the other hand, when contactor 513 is in connection with thecharge-holding conductor 34-544, the charge from the ion chamber leaksoff to the ground through potential divider 511, and the charge-holdingconductor system is held at a fixed bias potential determined bypotential source 510 and potentiometer 511.

If we suppose that a negative charge is left on the charge-holdingconductor 34-544 when relay coil 534 becomes energized, thus removingcontactor 513 from 34-544, then a positive charge from ion chamber 43collected at electrode 34-544 will cause the negative charge thereon tobe neutralized, supposing that charge from the ion chamber is permittedto collect over a sufficiently long period of time.

When this balance of charge is effected needle 34, FIG. 7, will nolonger oscillate in its AC field and the real image of the electrometerneedle will be in focus over optical slit 40 (FIG. 3 or 4). Thisproduces a signal in the photomultiplier circuit (1i of FIG. 1), whichin turn energizes relay 533 thereby de-energizing coil 534 by theremoval of potential 530. Immediately thereupon negative biasing chargeis returned to the charge-collecting conductor 34-544 and needle 34resumes its state of oscillation. In this manner the system operatescontinuously, first charging the conductor and needle and thenpermitting ions of opposite charge from the ion chamber to collect onthe charge-holding conductor.

It is clearly evident then in a series of such measurements the sameelectric signal that energizes relay 533 may also operate atime-measuring system to indicate the time interval, Δt, required forthe charge from the ion chamber to balance the known initial biasingcharge that is placed on the charge-collecting conductor 34-544 fromsource 510. Basically, the current, i, from the ion chamber may beexpressed in terms of the time interval, Δt, required for the equal andopposite potential, ΔV, caused by equal and opposite charge ΔQ(described above) to balance one another.

Thus i = ΔQ/Δt and i = C ΔV/Δt, where C is the capacitance of thecharge-collecting conductor 34-544.

We now return to a description of the reactor system as a whole.Referring now to FIG. 2, block 2L symbolizes a nuclear reactor or othertype of device, as, for example, a Production Process. Block 2Kindicates a control device for 2L. In the case of the nuclear reactor,2L symbolizes not only control rods but also an electro-mechanicalassemblage capable of inserting or retracting the shim rod. An on-linecomputer at 2i not only permits the control of the reactor to anydesired level of power output but also makes possible a completeanalysis of core power distribution. In addition, it is capable ofgenerating physics data and plant performance data for measurement,control and production of nuclear power.

For reactor application a suitable type of ion chamber tube may beemployed at 2a (e.g., the Westinghouse Compensated lonization ChamberWL-6377). It may be mounted in or near the core lattice for continuousmonitoring of neutron flux levels. Several such ion chamber type tubesmay be employed in conjunction with a given reactor core. In FIG. 2, itis seen that reactor 2L connects back to ion chamber 2a. This linksymbolizes the neutron flux level within the reactor core, at anyinstant, producing current within the ion chamber. Control unit 2k iseffective for removal or injection of control rods in the reactorlattice in response to the ion current levels maintained in the chamberby the neutron flux levels in the core.

The on-line computer 2i is usefully employed to receive and store inmemory flux level information in the form of digital time intervalreadings. It is capable of output signals to control unit 2j which inturn controls both the electrometer bias potentials at 2e as well as thereactor-power levels by means of control 2k.

NUCLEAR REACTOR

We consider now the details of reactor control. We may assume thatnumbers, representing time interval values, which are proportional tothe ion level in chamber 2a and therefore also proportional to the fluxof nuclear reactor 2L are continually being generated. Then, they arestored in time-interval memory 2b. This memory is buffer input storagefor computer 2i and may be considered as separate from or an integralpart of the computer.

The central computer core and processor of 2i may be employed on atime-share basis for the purpose 1) of determining the flux levelswithin reactor 2L due to ion levels produced in chamber 2a and, for thepurpose 2) of calculating and performing other programmed services forthe entire system.

Both the computation of reactor flux levels and the performing of otherservices for the system may be accomplished by computer software. C. E.Cohn in a patent publication (See References cited) gives an example ofa software, flow diagram and technique for reactor startup control.However, in place of software, logical hardware, which is notdistinguishable from the computer itself, may be employed forcomputation, logical decision and control. A computer system employinglogical hardware only, without stored program, may be preferred to thestored program computer especially for those applications where thecomputer operations are relatively few and are repeated on an almostcontinuous basis.

If central core memory and the central processing unit are not used on atime share basis, then the updating of flux levels from input, timeinterval data and the computing of excess reactivity may be accomplishedby a separate processor designed for this purpose incorporating its ownhardware for doing logic and even with its own core memory thusminimizing software requirements.

As pointed out above, logical hardware need not be distinguished fromthe computer itself; for the computer is a collection of logicalcircuits designed to perform various operations, including mathematical,physical (printing, plotting, opening or closing valves or movingreactor control rods) and decision operations, where selection is madebetween two or more paths of action. The decision capability gives thecomputer its tremendous power as a practical tool; and it is noted thatsoftware is not required for this capability.

As an example of a computer without software, one may cite the computercontrolled train which is not started, stopped or controlled by softwarebut by hardware, i.e., by the logical hardware that are integral partsof the many control computer units of the system.

An example of a computer applicable to our purpose is the IBM System/7which is both a sensing and controlling, online type of computer.

The principal quantity for calculation in reactor control is reactivity.Close to zero, positive reactivity, the e-folding time, i.e., theperiod, is large, while at zero reactivity, the period is infinite. The(excess) reactivity, rho, equals (K_(e) -1)/K_(e), where K_(e) is theeffective multiplication factor or reproduction constant.

The power in the reactor is given by

    P.sub.t = P.sub.o e .sup.+-.sup.t/T

where P_(o) is the power at some initial time, t = o and P_(t) is thepower at some later time t. The period, T is defined,

    T = K.sub.e g/(K.sub.e -l) =g/rho

where g is the average generation time of neutrons and is of the orderof 0.001 sec for thermal reactors which are prompt critical, and oforder 1 × 10⁻ ⁶ sec for prompt critical fast reactors, which reactors ifmade delayed critical are amenable to normal control procedures asdescribed herein for automatic control with this invention. Thegeneration time of neutrons is of order 0.1 sec if the reactor isdelayed critical. Reactor power is proportional to the average neutronflux density. Thus, power will also be proportional to the ion level inchamber 2a. At critical, K_(e) = 1; but if the excess reactivity ispositive, K_(e) is greater than 1; and if the excess reactivity isnegative, K_(e) is less than 1.

If there is a positive excess reactivity, then after one period thepower goes up by a factor of e ≃ 2.72. Thus, if one supposes a near zeropositive reactivity when the reactor output is for example, 100megawatts, then, at the end of one period, the reactor power will be2.72 × (100) megawatts.

Close to the zero reactivity, reaction times are relatively long so thatthe control rods, which take care of excess reactivity might easily bemanipulated by hand. This shows that when a reactor is being operated,since reactivity is always kept close to zero, there is never a squeezeon time for automatic control by means of a computer. It is usually ashim rod that controls the slight excess reactivity while a number ofrods are adjusted in such a way as to make the excess reactivityslightly positive so that the shim rod easily controls the excess.

FOR AUTOMATIC CONTROL OF A REACTOR:

1. there must be a set schedule of power levels to be maintained,

2. A sensing device for obtaining neutron flux data from the reactorcore,

3. A method of calculating the reactivity and the power level,

4. A control device in the reactor; this is a control or shim rod;automatic control requires that this control rod be motorized; or thatan electromechanical device be supplied capable of inserting the rod forabsorbing the positive excess reactivity and retracting the rod forincreasing the reactivity; one or more motors -- convenientlystep-motors that take one step in response to a single power pulse --may be used for this purpose,

5. A method of calculating the amount of control required for the rod isrequired; if a step motor is employed one must calculate the number ofpulses required to move the rod a distance to increase or decrease thereactivity by a certain amount; hence, the rod must be calibrated,

6. An on-line computer interfaced with the sensing device and thecontrol device which is capable of making all necessary calculations,

7. The rod calibration data must be in the computer together with astored program and the schedule of power levels to be maintained.

Returning now to the description of FIG. 2, control logic, symbolized at2j, is interfaced with on-line computer 2i. (Unit 2j may be consideredan itegral part of the on-line computer.) Internal switching symbolizedat 2j has two functions: It is the switching for control-rod system at2k and secondly, it is switching, providing adjustment for thepotentiometers at 2e that control the electrometer sensitivity. Thissecond control is a convenience but is not essential for the automaticcontrol of the entire system.

From high resolution timer and counter at 2g, digital time-intervalinformation is transmitted over a multiple, direct wire interface tobuffer memory at 2h and again through another such multiple, direct wireinterface between memory (buffer) 2h and memory of computer 2i. Theseinterconnections and scanning are accomplished in a conventional manneras used for transmitting pulses of digital information and may beconsidered as internal to the computer or as a scanning operation as ina card reader.

The on-line computer signals that control the switching logic at 2j maybe generated by software and/or hardware in the computer processor bydetermining the level of (excess) reactivity. Usually, a series ofpulses transmitted via solid state or relay switching at 2j andinterfaced with direct wire or through multiplexer channel techniques,drives the forward or reverse control of (step) motor (or motors) toinsert or retract the control (shim) rod indicated at 2k. It will beevident that various speeds of insertion and retraction and/or lengthsof insertion may be computer generated responsive 1) to the level ofreactivity observed and, 2) to the known calibration of the control rod.Thus, solid state or relay switching, multiplexed or direct wireconnected, applies power pulses to the motor controlling theshim-control rod of the reactor. The number of pulses transmitted to thestep motor control is calculated and is dependent, basically, upon thelevel of excess reactivity sensed.

Control logic and switching at 2j that is capable of changing theelectrometer sensitivity by pulsing a step-motor connected to drive apotentiometer at 2e (which, in turn, supplies an increase or decrease ofpotential across the electrometer binant electrodes), is made responsiveto the magnitude of the time interval readings received from the highresolution timer and counter at 2g. Let us suppose that the desiredspeed of response for the time-intervals are to be greater than 10seconds but less than 15 seconds. A software routine compares each timeinterval with these time requirements. Resultant upon the detection of asignal outside these bounds and by means of a stored-program-computercalculation the required number of pulses are transmitted throughcontrol logic and switching at 2j to step motor (or motors) at 2e. Thepulse or train of pulses (based on computer stored calibration data)increases or decreases the potential across the electrometer binants tobring the time-interval readings into line with the programmedrequirement.

Returning to a discussion of control 2k, if it is desired to change thereactor power level, this may be done by control rod adjustment. Let ussuppose a new higher level of power is required from the reactor. Ifsoftware is employed the new power level is read in either from card orcomputer keyboard. Let us suppose that after each reactivity computationthe average power level is also calculated and compared with theassigned power level. When the newly assigned higher power level issensed a stored program routine thereupon calculates the pulses requiredfor retracting the control rod so as to reach the new power level.Usually this is done in stages, alternately making reactivity readingsand thus approaching the newly assigned power level in gradual steps.The speed of the on-line computer easily controls and monitors thisgradual increase in power.

Switching logic at 2j may well be considered a part of the modernsensing and controlling computer. Interfacing of the modern on-linecomputer permits receiving and transmitting of either digital or analogsignals from and to sensing instruments and control devices. Theinterfacing techniques of the art permit either digital or analoginterfacing to either adjacent or distant equipment. Interfacingtechniques are outlined in Table 1.

TABLE 1 Interface Techniques

1. DIGITAL MODE -- Reading contacts for open-closed condition - This isthe language and mode of the digital computer -

A. single Wire (plus ground)

1. Connects the single contact of the sensing instrument to the computerinput for binary (off-on) scan.

2. Multiplexer Technique -- implies two or more signals (pulses) sentconsecutively on the same line and requires a scanning device at bothends of line. This is particularly adapted to long distance interfacingas between buildings or cities.

B. multiple Wire

1. Each contact of a digital sensor output is connected to the receiverstation (computer or other station being interfaced) for scanning.Multiple wire interfacing may be used for digital scanning with any basesystem of counting but normally is more feasible with short distanceinterfacing.

2. Multiplexer Techniques may be used for near-by or long distanceinterfacing. It is well-known how coding may be used to reduce thenumber of wires and how a few wires may be used for transmission overcommon paths by a pattern of consecutive transmission of signals. Withinthe art, one could say, the number of patterns is almost unlimiteddepending upon the situation and taste of the designer.

Ii. analog mode -- reading voltage -

A. single Wire (plus ground)

1. Usually implies only one potential (between sensor contact andground) to be read. The scan rate, i.e., the repetitious reading rate ofthe same potential depends upon the circuit design and the requirementsof the system.

2. Multiplexer techniques are applicable for shaping signal (as withunit gain amplifier or multirange amplifier) and changing from analog todigital mode.

B. multiple Wire

1. This usually implies reading potentials from more than one sensinginstrument (one voltage per contact point). Near-by interfacing iscompatible with one (or two) wire for each voltage to be scanned.

2. Multiplexing Technique here implies:

a. Scanning voltage points consecutively -- (thus reducing the number ofwires in the case of long distance transmission.)

b. Shaping signal as required by unit-gain or multirange amplifier.

c. Changing analog to digital reading.

HIGH RESOLUTION COUNTER AND TIMER

The high resolution counter and timer shown in FIG. 1 at 1h, 1i, 1j, 1kand 1L (also in FIG. 2 at 2g) employs a source of high and low frequencypulses fed to a counter, which counter is turned on and off by thephototransducer signal generated by the optical slit system. Digitalreadings from the counter represent elapsed time-intervals betweensuccessive phototransducer signals or, by an arrangement of circuitlogic, time intervals between a predetermined number or batch ofphototransducer signal.

Referring to FIG. 1, a pulse source 1i is capable of outputting severalfrequencies. A high and a low frequency, at a minimum, are desirable forthe general run of applications. The utility of the low frequency isseen in a system that operates on an intermittent basis. For example, ifa system is to be used for measuring the half life of longer half livedisotopes, operation on an intermittent basis is desirable. During theintervals when measurements are not taken it is desirable to keep anaccurate measure of this "off" time. For the "off" time measurement,then, the pulse source 1i is operated at the lower freqency. The gateshown at 1j, controlled by logic 1h, thereupon permits the primarycounter to collect pulses at a slower rate. Thus, the lower frequencyprevents the accumulation of a number of counts beyond the primarycounter capability. However, when it is desired to measure radiationwhere the time intervals are short, the high frequency pulses fromsource 1i are used. Fast counting with higher frequencies permits one toobtain in a short counting interval as many significant figures aspossible.

It is understood that the control logic indicated at 1h and 1L in FIG. 1are not entirely separate units. In reality, they represent the logic ofthe entire system but are diagrammed as separate blocks so that the flowof control may be more easily represented.

The primary counter reading may be transferred out into a parallel,buffer memory, before it is read out into more permanent type of record;or it may be read out serially. However, whatever method of read-out isemployed a minimum (but constant) interval of time is lost. This deadtime, at most, is of the order of 1/2 second. In one instrument, a 0.75sec. counter has been employed to inhibit the primary counter during a0.75 sec. interval subsequent to the readout of the primary counter.Apart from this, the Primary Counter counts continuously. The dead timecorrection for the Primary Counter is updated at a later time in thesystem sequence.

In FIG. 8 is shown a schematic circuit diagram for an AC potentialsupply for the binants of the electrometer. The Shonka electrometerunder manual operation does not require precise AC zero adjustment norprecision phase adjustment, since a reversal of the motion of thepattern in the eyepiece indicates to the operator the exact instant forthe termination of a time interval reading. Nonetheless, underautomatic, continuous operation, it is required that the same sharpnessof focus be maintained throughout a series of measurements. Thissharpness of focus is controlled both by a phase adjustment 906 as wellas by the ground adjustment 904 of FIG. 8.

Indicated at 901 in FIG. 8 is a source of AC power which may beconveniently 60 Hz 125 volts. A variac is shown at 902. It may beemployed as the AC power level control, supplying potential to theprimary of the step-up transformer 903. For the Shonka electrometer theoutput of this transformer need not exceed 500 or 600 volts. The ACground adjustment at 904 together with the phase control at 906 aretogether important for maintaining the same sharpness of focus, as wehave said, of the electrometer needle when it is at rest in the ACfield.

At 905, isolation capacitors are shown. Capacitor 908 (about 30 mmf)slightly loads the circuit. The electrometer is shown at 33 withconnections for the circuit to its binants 20 and 21. The quartz fiber,the vibrating member of the electrometer is shown at 34.

Various methods may be employed to stabilize the AC null adjustment ofthe electrometer. For example, temperature control of the criticalcircuit elements of FIG. 8 will hold the electrometer in AC nulladjustment.

Another method is shown in FIG. 9. Suppose that DC bias is removed from34-544, the electromete's collecting electrode of FIG. 7, so that theneedle 34, is at AC null, except for the final adjustment of ground at904 and phase at 906 (FIGS. 8 and 9). At 931A FIG. 9, a photomultipliertube is shown connected through resistors 940 and 941 to ground. Adifferentiator circuit at 950 is employed to sense the rate of change ofcurrent in resistor 940. Assume that the output of 950 is positive whendi/dt of resistor 940 is increasing; is negative when di/dt isdecreasing and is zero when di/dt is zero. At 960 is indicated apolarity sensing circuit, a motor drive, and circuit logic foralternately driving, first motor 903 and grounding potentiometer 904,and then motor 905 together with phase potentiometer 906.(Potentiometers 904 and 906 are also shown in FIG. 8.)

Basically, the circuits of 960 do the following: they set in motionalternately motor 903 and 905; if di/dt is positive they reverse thedirection of drive of the motor; if di/dt is negative, they continue todrive the motor; if di/dt is zero, they stop the motor. Logic at 906 isalso programmed for two or more successive, double adjustments ofpotentiometers 904 and 906, first driving one, then the other; theadjustments occur automatically. Adjustments may be programmed to occurbetween a batch of readings of the instrument or even to interrupt aseries of readings. Such an arrangement will maintain the instrumentcontinuously in AC null adjustment.

SENSING DEVICES

Sensing devices are varied, and many types are known in the art ofcontrol. The tachometer, the pressure transducer, the thermocouple, theflowmeter and potentiometer as well as the basic ion chamber and varioustypes of counters are able to provide analog and digital information,useful in the control of automated systems.

New sensing devices which are basic to the present invention are thefollowing:

1. Ion chamber, electrometer optical digitizer

2. The light chopper

3. The optical digitizer

4. The optical tachometer

5. The flux-optical digitizer

6. The spectro-optical digitizer

7. The spectro line-intensified digitizer

Each of these sensing devices is an arrangement of instrumental partswhich together constitute a new device for obtaining digital or analogsignals.

The ion chamber, electrometer, optical digitizer employs an alternatingcurrent quartz fiber electrometer together with a high resolutioncounter and timer. It has been described by means of FIGS. 1-9. It isbasically a current digitizer.

The light chopper employs an arm mounted on a rotating shaft. The shaftand arm are so positioned relative to a mask containing an opticalaperture that, upon illumination by a source of electromagnetic flux,light pulses are produced and also photoelectric signals. The rotatingarm is so mounted that it decreases light flux at the optical apertureduring a portion of its path of motion. (See FIG. 10 later to bedescribed.) A phototransducer mounted opposite the source of fluxchanges the light pulses to electric signals. The entire arrangementincluding the phototransducer is called a light chopper.

The optical digitizer is a light chopper that employs a phototransducertogether with a counter-timer consisting of a constant source ofelectric pulses and a counter, together with gating and logic, capableof counting the phototransducer signals of the light chopper eithersingly and/or in batches over periods of real time so as to producedigital time interval readings related to the angular motion of theshaft of the chopper. Input to the optical digitizer is a rotatingshaft. (See FIG. 13.)

The optical tachometer employs a rotating arm attached to a shafttogether with optical slits and a phototransducer so that rates ofrotation may be measured. (See FIG. 11, later to be described.) Whenthis arrangement is used in conjunction with a high resolution counterand timer, it is called an optical tachometer. The shaft of the opticaltachometer may be driven by a rotating shaft (like the speedometer of anautomobile) or by means of a motor through a clutch.

The flux-optical digitizer is an arrangement similar to the opticaldigitizer except for the driving mechanism. (See FIG. 12, later to bedescribed.) A glance at FIG. 12 shows a radiometer-like structurecarrying rotating fins. At 12 and 13 of FIG. 12 arrows represent radiantflux. This flux may be electromagnetic, ion flux, a flux of electrons, aflux of neutrons, and so forth. Such flux includes, of course, the linespectra encountered in use of the various types of modernspectrophotometers. (Such flux also includes the ion flux encountered ingas chromatography.) Because this instrument measures flux, the entirearrangement including the rotating fins and the high resolution timerand counter, is called a flux-optical digitizer.

The spectro-optical digitizer is an optical digitizer driven by avariable speed motor (such as a D.C. voltage controlled type) which inturn is connected to the output of a photomultiplier-amplifier (orphototube-amplifier arrangement). The cathode of the phototube orphotomultiplier is arranged to receive one or more of the principalemission or absorption lines from the infra-red, visible or ultra-violetspectrum of a sample under measurement as is conventionally done bymodern spectrophotometer techniques. This entire arrangement fromspectral line source to the high resolution counter and digitizer iscalled a spectro-optical digitizer. It is shown in FIG. 15 in which areactant vessel containing material under observation is shown at 1000.

The spectro line-intensified digitizer is seen to be similar to thespectro-optical digitizer. It employs an image intensifier between theprism, line-selector (commonly used in a spectrophotometer) and thephotomultiplier and amplifier. The image intensifier may be required toobserve weak lines difficult to observe (in the infra red) andcharacteristic of various organic molecules. The arrangement is shown inFIG. 16 in which a reactant vessel containing material under observationis shown at 1000.

The prism, line selector is a mechanically rotatable prism used toproduce a spectrum of the sample (reagent product) under observation andcontains also controls to select any portion of this spectrum forfurther observation.

An image intensifier is an electronic device, containing a high voltagesource, capable of intensifying a very weak image focused at theintensifier input. These devices are producing spectacular changes anddiscoveries in the field of astronomy. Another arrangement employs imageintensifiers and camera as a sensing device for production systems. Herethe spectral image is intensified by one or more image intensifiers inseries. The output from the intensifiers is then scanned with a cameraand the scanned image is stored in digital memory. The stored image ishandled from there on as digital information and may be used as datawith a stored program or hardware to produce control for an automatedproduction system.

We now return to a more detailed description of the Figures.

FIG. 10 shows a plan view of an optical-aperture, rotating arm, lightchopper. It is intended for use in conjunction with a phototransducerand as such is called a light chopper. When used also in conjunctionwith a counter timer (already described, see high resolution counter) itis called an optical digitizer. The end of a rotating shaft is shown at20. The shaft carries an arm 34 rotating in the plane of the circle, 70,in direction, 10. An optical slit, 40, in a mask, 39, which is eitherclose enough to arm, 34 that optical flux incident on the slit and aphototransducer (not shown) may be interrupted, or a real image of thearm, 34, produced at optical slit, 40, may be employed to producephototransducer signals.

FIG. 11 shows an optical-aperture, rotating arm angle indicator. Therotating shaft is shown at 20. The shaft carries arm 34 which isattached to a spring return mechanism shown at 8. Essentially thedevice, used in conjunction with one or more phototransducers and alight source together with a counter-timer is a rate meter, producingsignals whenever the arm (or its real image) decreases light flux at anaperture. These signals may be used to start and stop the counter-timeras well as to control a clutch which in turn may be employed to drivethe rotating shaft. The circle at 70 shows the plane of motion of thedeflecting arm 34. Mask 39 contains optical slits 40, 41 and 42. Theplane of the slits may be close enough to arm 34 to permit the armitself to interrupt light flux at the slits or, if at a distance, thereal image of arm 34 may be employed to obtain photoelectric signals.Alternately, mask 39 may be made adjustable so that with only one slit agiven deflection may be monitored and maintained.

FIG. 12 shows a plan view and a side view of a radiometerlike structure.It is a flux driven, optical aperture rotating arm light chopper and ispart of an arrangement called a flux-optical digitizer. Shaft 101carries two sets of vanes upon which radiant flux at 12 and 13 impengesas in a radiometer. Vane pairs 10 and 11 as well as pairs 20 and 21 arecoated on one side so that the radiant flux at 12 and/or 13 can driveshaft 100 in rotation. The coating may be opposite on the pairs (notshown in FIG. 12) so that the shaft rotation effected by the pairs, isin opposition. For light pressure measurements this assembly of vanesshould be maintained in a vacuum. The shaft also carries an arm, 34which is able to modulate light flux shown at 14, illuminating slit 40.Collar, 100 mounts arm 34 and permits its adjustment.

Suppose radiant flux 12 is a constant, standard known source of flux,capable of producing a given rotation of shaft, 100. An unknown flux at13 can be measured if either the real image of the arm or the arm itselfinterrupts light flux, 14, incident upon optical slit, 40. It isunderstood that this device is to be used in conjunction with aphototransducer together with a counter and timer. When this is done theentire arrangement is called a flux-optical digitizer. See FIG. 14.

PRODUCTION SYSTEMS

Under the general name of production systems I wish to describe varioustypes of production apparatus, systems and reactions which linked bycomputer and by means of sensing and control elements may be automated.

If one makes a general analysis of the production system he will findthe following elements:

1. A process where different states may be distinguished,

2. A process where some quality distinguishing the state may be measuredby a sensing device,

3. A process in which the distinctive quality may be controlled by acontrol device.

The general analysis will also reveal that to automate such systems oreven to operate them one further needs

4. A linkage for the system (possibly found within the system itself)consisting of:

a. Interconnection (at least logical if not physical or mechanical) ofsensing and control devices,

b. Use of information from the sensing device, to

c. Manipulate the control device. This is sometimes called "feedback".

The analysis also reveals that the more powerful linkage will have thefollowing properties:

d. Capability for mathematical computation,

e. Capability of making logical decisions.

It should be clear that production systems, taken in this wide sense,include planes flown by human or automatic pilot and autos driven at aconstant rate of speed either by a person or by a gadget that holds thespeed at a set value.

PLUTONIUM PRODUCTION

We have already described the production of power by means of a reactor.Not greatly different is the production of plutonium in that with thecomputer linkage for control of the process one may compute theplutonium output. In general, the plutonium rate of production isproportional to the reactor power level. Hence the computer must log theintervals for each power level of operation. For an unenriched thermalreactor with carbon moderator the output is roughly one gram ofplutonium per megawatt day. The old (wartime) reactors at Hanford wereunenriched. An enriched reactor produces less plutonium. In general, theamount of plutonium produced depends upon several factors, for examplethe enrichment of the fuel and the geometry of the lattice structure.

Water moderated reactors require enrichment (unless heavy water isused). Hence the boiling water and pressurized water reactors requireenrichment and thus would produce less plutonium.

It can be seen, then, that a stored program may contain all thenecessary information for calculating the plutonium productioninventory.

GASEOUS DIFFUSION SEPARATION

Another type of production system is the gaseous-diffusion separationplant employed for the separation and concentration of U235 from U238.As a first step toward the automation of the system one requires asensing device that can distinguish the various levels of enrichment ofU235. The sensing device suggested by this invention requires a probingbeam of neutrons, preferably thermal neutrons, and an absorption paththrough which they must pass. The absorption path contains uraniumhexafluoride and such paths and sensing instruments may be supplied atvarious stages of the separation where it is desired to monitor andmeasure the U235 concentration. After neutrons from the probing beampass through the absorption path they are directed to strike one of therotating fins of the flux-optical digitizer. As the separation processproduces higher and higher levels of U235 at a given instrument locationthe thermal probe beam is further and further attenuated and therotating fins of the flux-optical digitizer, rotating in and out of thebeam, undergo less and less momentum exchange with the impacting thermalneutron beam. Thus the speed of rotation will be decreased and the timeintervals from the digitizer will increase.

Control of the gaseous diffusion process requires control valves forvarious purposes. First, when a desired enrichment of U235 is attained ableeder valve draws off the gaseous product. Again routing valves areemployed to reroute the unfinished gaseous products.

REACTOR CONTROL

The flux-optical digitizer may also be used in conjunction with neutronsfrom a reactor core to measure core flux. By employing neutrons, forexample, thermalized neutrons from the reactor core and by adjusting thebeam for incidence on the fins of a flux-optical digitizer one mayobtain readings related to the core flux levels. With an on-linecomputer interfaced both, with the flux-optical digitizer and thecontrol rod mechanism, and by means of a stored program, one mayautomate the system. Of course, for most applications the instruments ofthis invention require calibration.

CHEMICAL REACTIONS

A chemical reaction together with the vessel or vessels in which it isproduced and maintained may be thought of as a production system. Manyreactions may be monitored and controlled by employing the new sensingdevices described in this paper.

As an example let us suppose a vessel contains copper sulfate solutionat some concentration. Now just as one measures the concentration bymeans of an optical spectrophotometer so one may employ thespectro-optical digitizer to obtain digital output. The digital readingswill correspond to the intensity of lines under measurement.

If the copper sulfate solution is supplied with electrodes theconcentration may be controlled by passing current through the solution.A current passing in one direction will remove the sulfate ion and,passing current in the reverse direction will bring it back intosolution, supposing the electrodes are such that deposition takes placeonly on one electrode. It should be clear that by means of an on-linecomputer, capable of sensing the molecular-ion concentration of thesulfate ion as just described, and by also controlling current in onedirection or the other through the solution according to a schedule ofconcentrations, as may be required, the whole process may be automated.It is understood that the computer may also calculate the currentrequired to produce a given required concentration starting at a givenmeasured concentration, since a current of one Faraday will depositone-half mole of copper. To control current in the cell one may employ astep-motor driving a rheostat in series with a voltage source and thecell itself. The step-motor is interfaced with the on-line computerwhere a stored program is employed to produce control for the flow ofcurrent in the cell and thus to maintain the solution concentrationaccording to any desired schedule.

Another example is of an ionic reaction employing temperature control.See Laboratory Physical Chemistry by Oelke/M.A.C.T.L.A.C. (1969) VanNostrand Reihnold pg. 328 and sqq. The reaction involves an aqueoussolution of potassium iodide and potassium persulfate forming freeioding. The free iodine concentration may be sensed by a spectro-opticaldigitizer. The principal iodine spectra is brought to focus on thecathode of the photomultiplier. The digital output is interfaced to thecomputer. Temperature sensors in the reactant are also interfaced to thecomputer. The computer is of the on-line type with stored program andhas internal capability of scanning all input sensing points. Because ofstored program capabilities a wide range of control is possible.Calibration data is included in computer memory so that the digitalresponse of the spectro-optical digitizer is related to the solutionconcentration of the free iodine. Control of the iodine concentration isby supplying a level of heat to the reactant. For this control arheostat controlled by a step-motor may be used to change the heatingcoil wattage at the reactant vessel. The stored program calculates thenumber of pulses required to change the wattage of the heater. Of coursethe step-motor is digitally interfaced to the computer.

It is understood that there are many chemical reactions for which anincrease or decrease in molecular concentration is not measurable byobservations employing the visible spectrum. For such reactions themodern techniques of the infrared and ultraviolet spectrophotometer arevery useful. Thus, employing absorption or emission lines in theinfrared or ultraviolet and directing these lines upon the cathode ofthe spectro-optical digitizer one may obtain measurements of molecularconcentration levels. As with the spectrophometers the use of thespectrooptical digitizer requires standardization. This implies a curve,or data for use in the computer, by which the response from a particulardigitizer may be read as a concentration. This is possible if theinstrument has been previously calibrated against samples of knownconcentration for the reaction system in question.

FIG. 17 shows a reactant vessel at 1000 carrying a substance to bereacted which is under temperature control and spectral observation.Another reactant shown at the rectangle labelled "reagent source", isbeing introduced into vessel 1000 through a valve that is controlled bya pulse motor which, in turn, is computer operated. The spectro-opticaldigitizer, in turn, supplies information to the computer indicating theeffect of the reagent in driving the chemical reaction.

One method of controlling temperature for the reaction is shown in FIG.17 and is under computer control. A source material for temperaturecontrol is stored as shown by the rectangle in FIG. 17, and may bepumped at any desired rate as required through coils shown at 200. Thevalve and pump controlling this flow are also pulse motor driven andlikewise under computer control. In a similar manner, catalysts may alsobe introduced to the reactant vessel 1000 and flow itself within thevessel may likewise be automated. Thus a highly complex control may beused to obtain reaction velocities and concentrations of reactants. Thecontrol of temperature and other physical properties of reagents ormaterials being synthesized are thus exemplified by the control shown inFIG. 17. In general, valves may be pressure operated or by means ofmotors which may be of the step variety and the reagent entry valve ofFIG. 17 between vessel 1000 and the reagent source might equally well beof the pressure variety, and computer operated.

SYNTHESIZING MOLECULES

Although the last two examples of controlled chemical reactions areabout the simplest possible, it should be clear that the types and kindsof chemical reactions amenable to computer control are almost unlimited.A few years ago, the synthesis of protein molecules in the laboratorywas accomplished. Some workers have done this painstakingly by hand.Others have used computer techniques. Since the number of atoms in aprotein molecule is so large (from 10,000 to over a million) no onewould attempt to synthesize such a molecule from its atoms. However,from amino acids and other products available in quantity, man's foodsupply, one day, may come from computer controlled synthesizingprocesses. It is easy to see that only the computer could handle thecomplexity of preparing a protein or carbohydrate molecule's components,speeding reactions with the appropriate enzymes, controllingtemperatures, pressures and radiant energy and assembling each reactantmember at the proper time and place in the molecule structure, thus toproduce life sustaining food for man.

It is said that each person through life requires an acre of land, on anaverage, for growing the food that sustains him. Food snythesizing, in asystem that operates day and night -- instead of once or twice a year,as for crops -- may, one day, produce food, on an acre of land, such asto have, on an average, a human sustaining capability in the thousands.

PULP MANUFACTURING PROCESS

In the initial stage of the paper making process, even if only partiallyautomated, there may be many sensing elements and there can be manycontrol devices. Among the former are flow meters, pressure gauges,temperatures sensors, counters, ph value meters,color-quality-measurements as well as measurement of consistency of thepulp stock. Among the control devices there are a large number of motordriven valves where a step-motor controls both a valve and apotentiometer as are the commercially available Foxboro types. Thesevalves may control steam, water or other types of flow. Water may beadded or removed from the pulp slurry suspension to maintain the correctconsistency for each stage of the process. As a flow-meter the opticaldigitizer of this invention might be employed. For this purpose a paddlewheel is mounted in the pipe conveying the pulp slurry. For a 3%consistency the paddle wheel rotates more rapidly than for a consistencyof 5%. By driving the optical digitizer from the paddle wheel shaft theconsistency may be monitored by an on-line computer which may bothcalculate the consistency and the water valve control setting needed tochange the flow to a given desired consistency. When both the opticaldigitizer and the pulse motor driving the valve are interfaced to thecomputer this operation may be automated.

The bleaching process may also be monitored and controlled by an on-linecomputer. By use of the spectro-optical digitizer and by looking at thepulp flow by means of the reflected white light from the pulp, thebrightness of the pulp may be read at stages along the bleaching path.For this purpose, light reflected from the pulp is directed into thecathode of the photo-amplifier unit of a spectro-optical digitizer. Inthis way various intensities of brightness may be monitored anddigitized; upon interfacing of the digitizer with an on-line computerwith stored program, the necessary valve openings for flow of bleachingmaterials may be calculated and controlled.

Another example from the pulp industry is the monitoring of the pulprate of output from the driers for inventory and control purposes. Byemploying an optical digitizer that is driven by a rotating shaft at thepulp output end of the drier and press assembly, rates of production inreal time may be monitored. The digitizer is interfaced with thecomputer containing a stored program. Control may also be initiated fromthe computer according to a schedule and transfer of output from flatbale form to roll package might also be automated.

PETROLEUM REFINING

In the petroleum refinery there are hundreds of closed, control loopsthat regulate the flow of the liquid or gas fractions within theprocess. For these closed loops a wide range of sensing elements areconnected to the control devices by an instrument called an analogset-point controller. The sensing elements obtain either pressurereadings, flow, temperature, specific gravity, tank levels or, for theanalysis of the fractions themselves, a reading, for example, from a gaschromatograph. The controlling device is most often a valve.

The analog set-point controller is most often used with manual control.In one such type of controller the voltage derived from the sensingelement, say a flow meter, called SEV (sensing element voltage) isapplied to one arm of a Wheatstone Bridge. Another arm of the bridge hasa voltage derived from the control device, called CDV. A differencevoltage, DV, which is the amount the bridge is off balance (and foundacross the usual null-meter position of the bridge) is amplified andused to regulate the control device which for this application is amotorized flow control valve. While the difference voltage isapproaching zero the bridge drives to balance, changing the valveopening and hence the voltage CDV which in turn changes the flow andtherefore also voltage SEV until balance is reached.

For setting the flow to a new value the analog set-point controllerpermits the operator to manually unbalance the bridge. This may be doneby changing the resistance or ratio of resistance in the other two armsof the bridge. When this is done by hand a new difference voltage isgenerated which again drives the system to balance. This hand controlcalled the set-point control is calibrated and may be made to correspondto any desired opening of the valve regulating the flow.

Petroleum refineries are going more and more to automatic control thatemploys the computer and stored program especially for those controlloops where precision control, say of blenders, are reflected in costsavings not possible with manual control.

The optical digitizer may also find application to the measurement offlow in both liquids and gasses for this industry. A paddle wheel orpropeller driven by the flow may be connected to the shaft of theoptical digitizer and, digital output, after calibration, may beimmediately read by the operator as a level of flow. For automaticcontrol it may likewise be fed to the computer.

Again, for analysis of the fractions, the spectro-optical digitizer andan ion-chamber electrometer optical digitizer (the latter used after themanner of the gas chromatograph) would find many applications in thepetroleum industry.

It will be clear that these examples of PRODUCTION SYSTEMS are by nomeans complete. Other applications will be found in almost everyproduction line and maufacturing process. Thus in the fields of glassmanufacturing, food preparation, water control such as used for a city'swater supply in water purification as well as in the evaporation processwhere desalinization of sea water is carried out, steel maufacturing andso on. Important to notice is that the fully automatic control of theseprocesses, employing the stored program concept, often pays for itselfin process efficiency.

From the foregoing and having presented my invention, what I claimis:
 1. In a power production system,a. a sensing device called anion-chamber-electrometer-optical digitizer comprised of:1. an ion sourceand an electrometer means; said electrometer being an alternatingcurrent quartz fiber type; said electrometer connected to said ionsource;
 2. a source of electromagnetic flux;
 3. an object illuminated bysaid source of flux;
 4. said object illuminated by said flux being theneedle of said electrometer;
 5. a focusing means for said flux, a realimage of said needle of said electrometer;
 6. a mask opaque to saidflux, containing an aperture;
 7. said mask in focal plane of saidfocusing means together with said real image so that said aperture andsaid real image may come into overlapping relationship;
 8. aphototransducer positioned adjacent said aperture to receive saidelectromagnetic flux from said aperture;
 9. a transducer signalgenerated responsive to the presence of said real image of said objectat said aperture resulting from the change of flux reaching saidtransducer;
 10. a counter-timer apparatus for measuring and recordingtime-intervals between said transducer signals; said counter-timerapparatus being a high resolution counter and timer; b. said powerproduction system being a nuclear reactor; c. said ion source being achamber, and said chamber being so positioned as to be responsive toneutron flux level of said neuclear reactor; d. a control device forsaid nuclear reactor, comprised of:1. motorized control rod sopositioned that said control rod may be inserted into core of saidreactor or may be retracted from the core of said reactor; e. a linkagebetween said sensing device and said control device consisting of:1. anon line computer interfaced to said counter-timer apparatus of saidsensing device and also to said motorized control rod; f. said on linecomputer effecting control of said control device responsive to saidtime-intervals from said counter-timer apparatus of said sensing device.2. In a power production system as described in claim 1,a. said on linecomputer incorporating a stored program.
 3. In a power productionsystem, in combination,a. a sensing device called anion-chamber-electrometer-optical digitizer comprised of:1. an ion sourceand an electrometer means; said electrometer being an alternatingcurrent quartz fiber electrometer; said electrometer connected to saidion source;
 2. a source of electromagnetic flux;
 3. an objectilluminated by said source of flux;
 4. said object illuminated by saidflux being the needle of said electrometer;
 5. a focusing means for saidflux, a real image of said needle of said electrometer;
 6. a mask opaqueto said flux, containing an aperture;
 7. said mask in focal plane ofsaid focusing means together with said real image so that said apertureand said real image may come into overlapping relationship;
 8. aphototransducer positioned adjacent said aperture to receive saidelectromagnetic flux from said aperture;
 9. a transducer signalgenerated responsive to the presence of said real image of said objectat said aperture resulting from the change of flux reaching saidtransducer;
 10. a counter-timer apparatus for measuring and recordingtime-intervals between said transducer signals; said counter-timerapparatus being a high resolution counter and timer; b. said powerproduction system being a nuclear reactor; c. said ion source being achamber, and said chamber being so positioned as to be responsive toneutron flux level of said nuclear reactor; d. a control device for saidnuclear reactor, comprised of:1. motorized control rod so positoned thatsaid control rod may be inserted into core of said reactor or may beretracted from the core of said reactor; e. a linkage between saidsensing device and said control device consisting of:
 1. an on linecomputer interfaced to said counter-timer apparatus of said sensingdevice and also to said motorized control rod;2. said on line computerincorporating a stored program; f. said stored program and said computereffecting control of said control device responsive to saidtime-intervals from said counter-timer apparatus of said sensing device.